The seniors in chemical engineering are midway through finding solutions to practical issues in their Senior Design Clinic.

By Thomas Guengerich

This is the fifth in a series of articles about the senior design classes in the engineering programs at New Mexico Tech. Previously profiled were the Electrical, Mechanical, Materials and Petroleum Engineering. Next up: Civil Engineering.

SOCORRO, N.M., March 30, 2009 – The seniors in chemical engineering are midway through finding solutions to practical issues in their Senior Design Clinic.

Ten students are working in three teams to address issues of global consequence along with their professor Dr. Robert Bretz.

One team is trying to develop an environmental friendly gasoline additive. The other two teams are working on different systems and procedures to create hydrogen. One team is working with domestic wastewater treatment systems. The other is trying to perfect a system to harvest hydrogen from algae.

Samantha Miranda, Leanna Marquez and Kauotar Abbou Oucherif are trying to develop methodology for making ethyl tert-butyl ether, or ETBE. In the United States, methyl tert-butyl ether, or MTBE, is the standard gasoline additive.

The team has researched an American patent for producing ETBE, but the public records say very little about the chemical process to create ETBE and the patent-holders were not inclined to share information.

The students found a Spanish company that produces ETBE and has opened a dialog with company officials about methodology. From the Spaniards, they are learning the details about splash-blended ethanol.

“They know the process and the design scheme,” Abbou Oucherif said. “They know the hardware and operating procedures.”

Most of their research is simulation and modeling – and not benchtop chemistry. They have designed a process flow diagram, process and instrumentation design and operating procedures. As the spring semester progresses, they will look at equipment specifications, hazard and operability studies and their presentations.

However, in addition to modeling, simulation and scientific research, the team is also investigating the market for ETBE – or lack thereof.

“We are looking at the economics – economic analysis, economic constraints and the social, political and geographical constraints,” Marquez said.

The development of a market for ETBE in the United States would require significant political policy change, Abbou Oucherif said.

“Nobody in the United States is pushing to switch from ethanol,” she said.

In the United States, most MTBE is corn ethanol. The technology for making MTBE is well-developed and the industry is mature. MTBE was first introduced as a gasoline additive in the late 1970s to increase oxygenation, to combust gasoline more thoroughly and, hence, reduce hazardous emissions.

More recent studies show that MTBE creates environmental risks, some of which would be mitigated by converting to ETBE. In Europe, ETBE is used more widely – not because of environmental concerns, but because of tax breaks offered to ETBE producers.

Without a changing of the political winds, proponents of ETBE face an uphill battle to replace MTBE as a gasoline additive.

The other two teams are examining hydrogen, albeit from completely different sources.
Kerri Harvey, Zach Peterson and Annie Hohmann are designing a theory and system for extracting industrial-grade hydrogen from municipal waste water. Harvey said the team wanted to examine a green technology. In this case, their system could harvest energy from sludge that would otherwise be dumped in landfills.

They are examining a multi-step process that would employ a plasma reactor and separation columns to filter and distill municipal waste in basic elements.

“We’re making a detailed instrumentation design,” Harvey said. “We’re coming at this problem like engineers – specifying every valve and every piece of equipment.”

At its simplest level, their system would separate waste into basic molecules like water, carbon dioxide and carbon monoxide, then extract the 99.997 percent pure hydrogen.

“The biggest challenge is that municipal waste doesn’t come in constant composition,” Harvey said. “The chemical composition changes by city, by time of day, by time of year.”

Peterson said they are looking for a methodology that will work with a variety of chemical compositions.

“We want to find a process with large limits where we can run a bunch of stuff through it and get the product we want,” he said.

The models they’ve developed so far would be rather expensive. Harvey said the initial capital costs would be too great to make the investment worthwhile. A significant challenge is to fine-tune the system to make it more affordable.

Their goal is to produce hydrogen that can be used in fuel-cell transportation purposes. They are using the city of Albuquerque as a benchmark. They are shooting for a system that could handle the city’s municipal waste and produce enough hydrogen to power the city’s fleet of busses.

“We want to reduce the cost of hauling sewage,” Harvey said. “Another great aspect is that the plasma reactor intensifies heavy metals, which are normally disposed of. The reactor takes sand and makes a sort of glass that is strong enough to use as a building material. So, there’s not a waste stream.”

Team No. 3 is also examining hydrogen production; however, they are looking at developing a means of using biological processes to create hydrogen. They are also looking closely at transportation and industrial uses.

Brock Romero, Britt Catron, David Meyers and Daniel Martinez found a patented process, while they are refining to make more efficient and economical.

They are considering a new heat exchange process with a combustion turbine. They are fine-tuning the system with an eye toward creating a self-contained electricity generation device that could be used by a household or a neighborhood.

“Right now, our system is designed for home use, but it’s too expensive,” Meyers said. “If we can optimize it, it’ll still probably be only used by wealthy residents with available land.”

That makes the current available market for home-based hydrogen power relatively small. The key development to advance hydrogen use will be storage, he said.

“Compression costs are a critical issue in hydrogen – and with natural gas, too,” Bretz said.